Transistorized voltage regulator



July 10, 1962 w. H. BARNARD TRANSISTORIZED VOLTAGE REGULATOR Filed Dec. 30, 1958 Q\ i a k R M Q M Q NN m NM. N N Q Q Q R. v Q 9 xx mm 0 Q .3 A Q \v N h INVENTOR. WIZLMM H. BAPNAPD ATTORNEY United States Patent Ofitice 3,044,006 Patented July 10, 1962 3,044,006 TRANSISTORIZED VOLTAGE REGULATOR William Howard Barnard, Westwood, N.J., assignor to The Bendix Corporation, a corporation of Delaware Filed Dec. 30, 1958, Ser. No. 783,919 3 Claims. (Cl. 322-28) The present invention relates to voltage regulators and more particularly to a transistorized voltage regulator for a DC. generator.

Heretofore, it has been the practice to employ a DC. amplifier mode of operation for a transistorized voltage regulator for a DC. generator as no A.C. voltage is available at the terminals of a DC. generator. This mode of operation has the disadvantage of relatively large losses in the transistors, thereby limiting the power output available from the transistor amplifier, or the ambient temperature capability, or a combination of both.

The present invention provides a transistorized regu- 1 proved voltage regulator in which losses are kept to a minimum.

Another object of the invention is to provide an improved voltage regulator for a DC. generator having a fast response.

The above and other objects and features of the invention will appear more fully hereinafter from a consideration of the following description taken in connection with the accompanying drawing, wherein one embodiment is illustrated by way of example.

In the drawing, the single FIGURE is a schematic diagram of a system embodying the invention.

Referring now to the drawing, a DC. generator is indicated generally by the numeral 1 and has a series field winding 2, armature 3 and shunt field winding 4. The armature 3 has the usual commutator and the output therefrom is connected by conventional brushes to output conductor 5 and through the series winding 2 to ou put conductor 6.

A voltage regulator indicated generally by the numeral 7 includes a reference bridge 8 and an amplifier 9. The reference bridge has a silicon zener diode 10 in one leg, a resistor 11 in an adjoining leg and a tapped resistor 12 forming the other legs thereof. One input of the bridge 8 is connected by a gas diode 13 and conductor 14 to the output line 5. The other input of the bridge 8 is connected by conductor 15 and secondary winding 16 of a transformer 17. In addition to the secondary winding 16, the transformer 17 has a primary winding 18 connected by conductors 19 and 20 to a suitable source of alternating current (not shown).

One output terminal of the bridge is connected by condoctor 21 to base 22 of a transistor 23 which forms the first stage of the amplifier 9. In addition to the base 22,

the transistor 23 has an emitter 24 connected by conductor 25 to the other output terminal of the bridge 8 and a collector 26 connected by resistor 27 to conductor 2-8. The emitter 24 of the transistor 23 is also connected by conductor 29 to base 30 of a transistor 31 which forms the second stage of the amplifier 9. In addition, the transistor 31 has a collector 32 connected by conductor 33 to the. conductor 23 and an emitter 34 connected by conductor 35 to base 36 of a transistor 37.

The transistor 37 forms the third stage of the amplifier 8 and has a collector 38 connected by conductor 39 to one side of the shunt field winding 4 of the generator 1 The other side of the winding 4 is connected by a conductor 40 to the conductor 28. A resistor 41 and rectifier 42 are connected across the conductors 39 and 40. Also, the transistor 37 has an emitter 43 connected by a rectifier 44 and conductor 45 to the output line 6. A resistor 46 is connected from the conductor 45 to the conductor 35. The conductor 28' is connected by conductor 47 to the input conductor 5. A capacitor 48 may be connected across the bridge 8.

In operation, the sensing bridge is connected across the output of the generator with a portion of the output voltage dropped across the. gas diode. An alternating current is impressed upon the input of the bridge. The capacitor connected across the bridge shapes the alternating current into a saw-toothed Wave form. The reference bridge is balanced and so arranged that a line voltage increase gives a decrease in output and a decrease in line voltage gives an increase in output.

The output of the reference bridge is a saw-toothed approximation with an average D.C. level inversely proportional to the generator line voltage. This output is applied to the transistor amplifier which is designed to be well overdriven by the saw-toothed wave form. The output of the amplifier is approximately a square wave. Any change in the input voltage changes the width of the square wave output. Extreme line voltage changes, such for example as transients, cause sufiicient change in the applied D.C. level to turn the first stage completely on or ofl depending on whether an undervoltage or overvoltage occurs.

The output of the first stage of the amplifier is applied to two additional stages, each being designed to be slightly overdriven. Thus, each stage is either in an on or oil condition, thereby keeping the power dissipation of each stage to a minimum.

Although only one embodiment of the invention has been illustrated and described, various changes in the,

form and relative arrangement of the parts, which will now appear to those skilled in the art, may be made without departing from the scope of the invention.

What is claimed is:

l. A voltage regulator for a DC generator having an excitation winding and an output winding comprising a reference bridge, circuit means connecting the input of said reference bridge to the output of said generator, said reference bridge being connected to provide an output inversely proportional to the input deviating from a predetermined value, a transistor circuit adapted to be driven to an on or oil condition, means including an alternating current impressed on the input of said bridge to modulate the output thereof to control said transistor circuit, other circuit means connecting said transistor cira a 4- cuit for energization from said generator output, and References Cited in the file of this patent means connecting the output of said transistor circuit UNITED STATES PATENTS across said excitation Winding.

2. The combination as set forth in claim 1 in which Z' Evans et a1 Man 3 the output of said transistor circuit is a square wave in r, 2,731,550 Chase: fume which changes in the input voltage changes the Width of 2'767365 Gugg 1956 the Square Wave 2,809,339 Guggi Oct. 8, 1957 3. The combination as set forth in claim 1 and inclndg 3 in a ca acito connect d 0 th 'n ut f a'd f 1 6 ma ay 1 7 p r e SS e 1 p O s 1 re er 2,892,143 Sommer June 23, 1959 ence bridge to change the alternating current to a saw- 10 toothed wave form. 

